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Monday, August 10, 2015

Cave of Crystals

Protected by an ice-cooled suit, a researcher rappels into
the cave of Crystals. Unlike most caves, the Mexican cavern is extremely hot,
warmed by magma chambers underneath.

True Shapes

Explorers clamber through the enormous selenite crystals
that sprout from every surface of the Cave of Crystals. Scientists call the crystals’
sharp, regular shapes “euhedral,” from the Greek words meaning “true shape.”

MEXICO Some of
the glittering giants of Cueva de los Cristales, or Cave of Crystals, are more than 30 feet long (9m) and half a
million years old. But humans discovered the monly in 2000, when two brothers
were drilling nearly a thousand feet (305 m) belowe ground in the Naica mine,
south of Chihuahua in northern Mexico. Crystals embody order, with stacks of
molecules assembled according to rigid rules. For eons, groundwater saturated
with calcium sulfate filtered through the many caves at Naica, warmed by the
magma below. As the magma cooled, water temperature eventually stabilized at
around 136ᵒF
(58ᵒC).
minerals in the water converted to selenite, molecules of which were laid down
like tiny bricks over the millennia to form these massive crystals.

Explained by science

For more than half a million years, mineral-rich water
filtered through this cavern under Naica mountain, depositing molecules of
calcium sulfate in orderly stacks. Heated by magma deep below and insulated by
thick walls, the watery womb remained virtually unchanged, allowing crystals to
grow to immense proportions.

The naica mine

Veined with ore deposits rich in lead and silver, the Naica
mine would flood if the water table were not lowered by constant pumping. This
action also drained the Cave of Crystals. The mine holds similar caves with
samller crystals, named for the shape of their formations: Cave of Swords, Cave
of Candles, and Eye of the Queen.

Temperature Inside
the Cave

Readings have dropped about six degrees since its 2000
discovery because of the mine’s ventilation system.

How the megacrystals
formed

25 million years ago Volcanic activity pushes
magma toward the surface. Intrusions of mineral-rich fluid will be transformed
into one bodies and mineral that later from the crystals

1-2 million years ago Temperatures underground
decline and caves form, filled with mineral-rich water. Anhydrite, a type of
calcium sulfate, begins to dissolve into the cave water.

600,000 years ago The cave cools to roughly 136ᵒF
(58ᵒC),
the right temperature for calcium sulfate in the water to form selenite
crystals. Undisturbed, it becomes a nursery for giants.

Ca 1985 Miners unknowingly drain the cave as they
lower the water table in the mine with pumps. No longer immersed in water, the
crystals stop growing.